Optical recording medium and device for writing and reading information in and from the recording medium

ABSTRACT

The invention relates to an optical recording medium having a plurality of guide lines (1) and data regions (5) which are defined between adjacent guide lines and in which data is optically recorded. Each guide line (1) includes a start guide (2) indicating the leading end of the data region, clock guides (3) arranged at a predetermined interval to follow the start guide (2) and enabling synchronization during reading and writing, and sector marks (4) arranged at a predetermined interval so as to divide the data region (5) into a plurality of sectors. The clock guides (3) on adjacent guide lines are arranged in such a staggered manner that the clock guides (3) appear alternatingly in both guide lines. The data region having sector number writing portion (5a) provided in the vicinity of each sector mark (4) for writing a sector identification number to be written therein. This arrangement enables an easy recognition of a shift to the next data bit or to the next data bit writing position during reading and writing of the data. At the same time, the sector mark (4) improves the efficiency of the recording region.

BACKGROUND OF THE INVENTION

1. Technical Field

The present invention relates to an optical recording medium having aplurality of guide lines and data regions which are defined betweenadjacent guide lines and usable for optically recording data therein.

2. Background Art

Hitherto, an optical recording medium of this kind has linear trackguides and data regions.

Reading and writing of data are accomplished by a self-clock method inwhich synchronization is achieved by means of clock bits contained inthe data, while tracking is conducted to follow up a track guide.

The conventional optical recording medium, however, suffers from thefollowing problems due to the use of the self-lock method. Namely, oncethe lock of the tracking is broken due to, for example, a contaminant orflaw in the surface of the optical recording medium, reading of datafails until the next clock bit is read. In addition, erroneous readingof data tends to result after a relocking, due to the fact that there isno means for identifying the leading end of the data.

SUMMARY OF THE INVENTION

In order to overcome the above-described problems of the know art,according to the present invention, there is provided an opticalrecording medium having a plurality of guide lines and data regionswhich are defined between adjacent guide lines and in which data isoptically recorded, wherein each guide line includes a start guideindicating the leading end of the data region, clock guides arranged ata predetermined interval to follow the start guide and enablingsynchronization during reading and writing, and sector marks arranged ata predetermined interval so as to divide the data region into aplurality of sectors, the clock guides on adjacent guide lines beingarranged in such a staggered manner that the clock guides appearalternately in both guide lines, the data region having sector numberwriting portions provided in the vicinity of each sector mark forwriting a sector identification number to be written therein.

According to the invention, since clock guides are provided on guidelines such that clock guides on two adjacent guide lines appearalternately, it is possible to easily recognize that the head has beenmoved to the next data bit during reading or to the next data bitwriting position during writing.

According to the invention, each track as the data region is sectionedinto a plurality of sectors at a constant interval, and sector marksindicating the border between the adjacent sectors are provided on theguide line. Thus, each track is divided into a plurality of sectors. Inthe known recording mediums, one full track becomes unusable when a flawor a contaminant resides on the track. In contrast, according to theinvention, only the sector of a track which has a contaminant or a flawbecomes unusable, and other sectors of the same track still remainusable, whereby the efficiency of the recording region is improved.

In addition, since identification number of each sector is written inthe data regions subsequent to the guide line, it becomes possible todefinitely recognize and identify the sector. It is therefore possibleto promptly recognize the position of the sector when the tracking islocked again after accidental unlocking due to presence of a flaw orcontaminant on the surface of the optical recording medium.

In a preferred form of the present invention, the sector mark has alength which is n times as large the length of the clock guide, where nis an integer. This eliminates the necessity for synchronization becausethere is no offset of the timing between the binarized signal of theclock guide and the output signal from the PLL circuit.

According to another aspect of the present invention, there is providedan apparatus for reading and writing data from and in the opticalrecording medium, comprising: a clock guide reading section for readingthe guide line and attaining synchronism by using the read clock guides;data reading section for reading data using, as references, thesynchronizing signals derived from the clock guide reading section; anda writing section for writing data in the optical medium by using, asreferences, synchronizing signals from the data reading section; whereinthe clock guide reading section includes a binarizing circuit forbinarizing the clock guide read waveform, a PLL circuit for effecting a90° phase shift of the output from the binarizing circuit, one-shotmultivibrator circuits for producing synchronizing signals in responseto edges of the output signal from the PLL circuit, and a flip-flopcircuit for detecting the sector mark from the outputs of the binarizingcircuit and the PLL circuit.

Since the data bit needs to be written in the center of the clock guide,the risk for erroneous reading of data is eliminated despite anyfluctuation in the position and size of the data bit. In addition, theefficiency of recording of the data is improved because thesynchronizing signals are delivered in response rises and falls of theoutput signal from the PLL circuit.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of an embodiment of optical recordingmedium of the present invention;

FIG. 2 is an enlarged view of an essential portion of the embodimentshown in FIG. 1;

FIG. 3 is a block diagram of data reading and writing apparatus whichmakes use of the optical recording medium shown in FIG. 1; and

FIG. 4 is a time chart illustrating the operation of the apparatus shownin FIG. 3 for reading data from the optical recording medium shown inFIG. 1.

THE BEST MODE FOR CARRYING OUT THE INVENTION

An optical recording medium of this embodiment has a recording region 6as shown in FIG. 1. The optical recording medium, however, need notalways be of the card type shown in FIG. 1 but may be of other typessuch as disk type.

FIG. 2 is an enlarged view of the recording region 6. The recordingregion 6 has a plurality of guide lines 1 and data regions 5 betweenadjacent guide lines 1. The data regions 5 are the regions in which dataare optically recorded.

Each guide line 1 is composed of a start guide 2, clock guides 3 and asector mark 4, and serves as a tracking guide used during reading andwriting data.

The start guide 2 is provided on the end of the guide line 1 andindicates the position of the leading end of the data region 5. Theclock guides 3 have a predetermined width and are regularly arranged ata constant interval following the start guide 2. These clock guides 3are used for obtaining synchronization during reading and writing. Theclock guides 3 on two adjacent guide lines 1 are arranged in a staggeredmanner such that the clock guides on both guide lines appearalternately, thereby making it possible to recognize any shift of thedata bit during reading and writing of data. The sector mark 4 has alength which is equal to the total length of a plurality of clockguides, i.e., a length which is obtained by multiplying the length ofthe clock guide 3 with an integer. The sector marks 4 are provided onthe guide line 1 at a predetermined interval, thus defining each sectorof the guide line. In other words, each track is divided into aplurality of sectors by these sector marks. In the event that one of thesectors of a track is defective due to presence of a flaw orcontamination, only the defective sector becomes unusable while othersectors remain usable.

Data are written in the data region 5 using the clock guides 3 as thetime reference. A sector number writing portion 5a is provided in thedata region 5 near the sector mark 4. A bit representing the address ofeach sector is written in the sector number writing portion 5a, therebyenabling a clear identification of the sector position.

A description will be now given of an embodiment of the apparatus of theinvention for writing and reading data in and from the optical recordingmedium described hereinbefore.

The apparatus has a data reading section 11, a clock guide readingsection 12 and a writing section 13.

The clock guide reading section 12 includes a binarizing circuit 121 forbinarizing the reading output obtained by reading the clock guides 3, aPLL circuit 122 for effecting a 90° phase shift of the output from thebinarizing circuit 121, one-shot multivibrator circuits 123, 124 whichproduce pulses in response to rise and fall of the output of the PLLcircuit 122, and a counter which counts the falls of the pulses from theone-shot multivibrator circuits 123, 124 and capable of producing a readdemand signal when the count has reached a predetermined number. Theapparatus also has a flip-flop circuit 126 which detects the sector mark4 from the output of the binarizing circuit 121 and a signal obtained byinverting the output from the PLL circuit 122.

The data reading section 11 includes a binarizing circuit 111 forbinarizing the data reading output waveform, a serial-parallelconversion circuit 112 for conducting serial-parallel conversion of theoutput of the binarizing circuit 111 in accordance with the outputs ofthe one-shop multivibrator circuits 123, 124, and a buffer circuit forreceiving the output of the serial-parallel conversion circuit 112 inaccordance with the read demand signal of the counter 125.

The writing section 13 includes a parallel-serial conversion circuit 131for conducting parallel-serial conversion of the write data inaccordance with the outputs from the one-shot multivibrator circuits123, 124 and a load pulse transmitted from the CPU, and a writingcircuit 132 for writing the output of the parallel-serial conversioncircuit 131 in the data region 5 of the optical recording medium.

The operation of this apparatus for reading and writing data from and inthe optical recording medium shown in FIGS. 1 and 2 will be describedwith reference to a time chart shown in FIG. 4.

Since the output from the binarizing circuit 121 is shifted 90° by thePLL circuit 122, the output of the PLL circuit 122 rises or falls at themidst of each clock guide 3. The one-shot multivibrator circuits 123 and124 produce pulses which rise simultaneously with the rise and fall ofthe output from the PLL circuit 122.

The data binarized by the binarizing circuit 111 is serial-parallelconverted. Detection of the converted data is conducted by using therising pulses output from the one-shot multivibrator circuits 123, 124as the triggers. Namely, "1" is output when data exists in the midst ofthe clock guide, whereas, when no data exists, "0" is obtained as thedata detection output.

The falls of the output pulses from the one-shot multivibrator circuits123, 124 are counted by the counter 125 and, when the count value hasreached a predetermined value, the counter 125 outputs a reading demand.

In response to reading of the sector mark 4, the flip-flop circuit 126delivers a sector mark detection signal, in response to the output fromthe binarizing circuit 121 and the signal obtained by inverting theoutput of the PLL circuit 122. Reading of data is conducted on arecognition that the sector mark detection signal indicates the leadingend of the sector containing the data to be read.

The writing of data is conducted as follows. The parallel write dataderived from the CPU is converted into serial signals and the writingcircuit 132 writes the serial signals in the recording medium using therising pulses output from the one-shot multivibrators 123, 124 as thetriggers. Consequently, the data is written in positions between theclock guides 3.

The load pulse is transmitted from the CPU after detection of the risingedge of the read demand signal.

What is claimed is:
 1. An optical recording medium having a plurality ofguide lines and data regions which are defined between adjacent guidelines and in which data is optically recorded,wherein each said guideline includes a start guide indicating the leading end of an associateddata region, a plurality of clock guides arranged at a predeterminedinterval to follow said start guide and enabling a synchronizationduring reading and writing, and sector marks arranged at a predeterminedinterval so as to divide said guide line into a plurality of sectors,said clock guides on adjacent guide lines being arranged in such astaggered manner that said clock guides appear alternately in both guidelines, said data region having section number writing portion providedin the vicinity of each sector mark for writing a sector identificationnumber to be written therein.
 2. An optical recording medium accordingto claim 1, wherein said sector mark has a length equal to lengthobtained by multiplying the length of a clock guide with an integer. 3.An apparatus for reading and writing optical data from and to an opticalrecording medium comprising a plurality of guide lines and data regionswhich are defined between adjacent guide lines and in which data isoptically recorded,wherein each said guide line includes a start guideindicating the leading end of said data region, clock guides arranged ata predetermined interval to follow said start guide and enablingsynchronization during reading and writing, and sector marks arranged ata predetermined interval so as to divide said guide line into aplurality of sectors, said clock guides on adjacent guide lines beingarranged in such a staggered manner that said clock guides appearalternately in both guide lines, said data region having a sector numberwriting portion provided in the vicinity of each sector mark for writinga sector identification number to be written therein, comprising: aclock guide reading section for reading said guide line and attainingsynchronism by using the read clock guides; data reading section forreading data using, as references, the synchronizing signals derivedfrom said clock guide reading section; and a writing section for writingdata in said optical medium by using, as references, synchronizingsignals from said data reading section; wherein said clock guide readingsection includes a binarizing circuit for binarizing the clock guideread waveform, a PLL circuit for effecting a 90 degree phase shift ofthe output from said binarizing circuit, one-shot multivibrator circuitsfor producing synchronizing signals in response to edges of the outputsignal from said PLL circuit, and a flip-flop circuit for detecting thesector mark from the outputs of said binarizing circuit and said PLLcircuit.